X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imo-m14.mx.aol.com ([64.12.138.204] verified) by logan.com (CommuniGate Pro SMTP 5.1.0) with ESMTP id 1487099 for flyrotary@lancaironline.net; Thu, 19 Oct 2006 17:07:35 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.138.204; envelope-from=WRJJRS@aol.com Received: from WRJJRS@aol.com by imo-m14.mx.aol.com (mail_out_v38_r7.6.) id q.cce.9d69a7 (52449) for ; Thu, 19 Oct 2006 17:07:11 -0400 (EDT) Received: from FWM-D11 (fwm-d11.webmail.aol.com [205.188.160.203]) by ciaaol-r07.mx.aol.com (v113.6) with ESMTP id MAILCIAAOLR074-cce14537e8ff1b5; Thu, 19 Oct 2006 17:07:11 -0400 References: To: flyrotary@lancaironline.net Subject: Re: [FlyRotary] Re: Spark plugs Date: Thu, 19 Oct 2006 17:07:11 -0400 In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: wrjjrs@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MB_8C8C1D9AE25C5FF_980_4F75_FWM-D11.sysops.aol.com" X-Mailer: AOL WebMail 20836 Received: from 65.161.241.3 by FWM-D11.sysops.aol.com (205.188.160.203) with HTTP (WebMailUI); Thu, 19 Oct 2006 17:07:11 -0400 Message-Id: <8C8C1D9AE28285C-980-2A01@FWM-D11.sysops.aol.com> X-AOL-IP: 205.188.160.203 X-Spam-Flag: NO ----------MB_8C8C1D9AE25C5FF_980_4F75_FWM-D11.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii" Lynn, Obviously you have been there. The last time I told someone about "cement boil" at the center electrode they looked at me like I had three heads! FWIW when plugging and checking mixture on extreme 2-cycles, (World Championship Motorcycle F1), we would jet the plugs white as a sheet! None of that pleasant tan color everybody talks about. Of course we had a air density gauge in the tool box and would re-jet on the hour based on current density! If your engine has been idling, especially a rotary the plugs will look a bit fouled. Bill Jepson -----Original Message----- From: Lehanover@aol.com To: flyrotary@lancaironline.net Sent: Thu, 19 Oct 2006 12:17 PM Subject: [FlyRotary] Re: Spark plugs In a message dated 10/19/2006 1:32:36 P.M. Eastern Daylight Time, ALVentures@cox.net writes: I have been doing a lot of re-tuning of the mixture which may account for some of the dark deposits, but I'm considering a change of plugs soon. Just wondered what other recommendations might be out there regarding plugs, heat range, gaps. Lynn; I recall you weighed in on this before, but I didn't find it in the archives. Thanks, Al Paul Yaw is on the dyno every day, and has forgotten more about rotaries than I have learned. So, whatever he says to use, is the plug to use. Judging the plug's (and engines) performance by looking at it after a full power run and a clean cut is still a viable way to recover data on mixture and heat range. However, at aviation RPM, there is not much need for a real (Lethal) ignition system. Just about anything will work. We had the two distributor 12As turning over 9,000 RPM with good reliability. So, for racing we use R6725-115 NGKs with the gap at .010". This is an ice cold plug in heat range for a 12A (smaller than a 13B) making about 250 HP. So, why not use that? There is no need or advantage. These plugs are $25.00 each. They are hard to find. You will not be turning RPM where lighting the mixture is becoming difficult. At even 7,000 RPM the engine is hardly running at all. They will foul quickly. Running car fuel gets you a very dark clean cut plug reading as in fluffy black more like oil fouled. Most of that will be from just one second of idle power on car gas. Avgas works just fine for plug readings. A clean cut is from cruise RPM to stopped at the same throttle setting and ignition off. The guys looking through the eyepiece at the track are running racing fuel with lead in it. They are looking for cement boil around the center electrode. Flat black to no color on the shell face. No rounding of the electrodes. A hint of tan on the side of the porcelain facing the intake valve. Good luck on that one. Fractured porcelain and so on. From 9,000 on up, a good CD or CD with multi spark is a must, both power wise and misfire wise. So, a dark plug that has idled for just a second or so will look bad because the nose temp has dropped out of the operating temp range and collects phosphors from car gas or lead compounds fro avgas. it just looks bad. It will clean up when used hard again. Lynn E. Hanover ________________________________________________________________________ Check out the new AOL. Most comprehensive set of free safety and security tools, free access to millions of high-quality videos from across the web, free AOL Mail and more. ----------MB_8C8C1D9AE25C5FF_980_4F75_FWM-D11.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/html; charset="us-ascii"
Lynn,
Obviously you have been there. The last time I told someone about "cement boil" at the center electrode they looked at me like I had three heads! FWIW when plugging and checking mixture on extreme 2-cycles, (World Championship Motorcycle F1), we would jet the plugs white as a sheet! None of that pleasant tan color everybody talks about. Of course we had a air density gauge in the tool box and would re-jet on the hour based on current density! If your engine has been idling, especially a rotary the plugs will look a bit fouled.
Bill Jepson
 
-----Original Message-----
From: Lehanover@aol.com
To: flyrotary@lancaironline.net
Sent: Thu, 19 Oct 2006 12:17 PM
Subject: [FlyRotary] Re: Spark plugs

In a message dated 10/19/2006 1:32:36 P.M. Eastern Daylight Time, ALVentures@cox.net writes:
I have been doing a lot of re-tuning of the mixture which may account for some of the dark deposits, but I'm considering a change of plugs soon.  Just wondered what other recommendations might be out there regarding plugs, heat range, gaps.  Lynn; I recall you weighed in on this before, but I didn't find it in the archives.
 
Thanks,
 
Al
Paul Yaw is on the dyno every day, and has forgotten more about rotaries than I have learned.
So, whatever he says to use, is the plug to use.
 
Judging the plug's  (and engines) performance by looking at it after a full power run and a clean cut is still a viable way to recover data on mixture and heat range. However, at aviation RPM, there is not much need for a real (Lethal) ignition system. Just about anything will work. We had the two distributor 12As turning over 9,000 RPM with good reliability. So, for racing we use R6725-115 NGKs with the gap at .010". This is an ice cold plug in heat range for a 12A (smaller than a 13B) making about 250 HP.
 
So, why not use that?
 
There is no need or advantage. These plugs are $25.00 each. They are hard to find. You will not be turning RPM where lighting the mixture is becoming difficult. At even 7,000 RPM the engine is hardly running at all. They will foul quickly. Running car fuel gets you a very dark clean cut plug reading as in fluffy black more like oil fouled.  Most of that will be from just one second of idle power on car gas. Avgas works just fine for plug readings.
 
A clean cut is from cruise RPM to stopped at the same throttle setting and ignition off.
 
The guys looking through the eyepiece at the track are running racing fuel with lead in it. They are looking for cement boil around the center electrode. Flat black to no color on the shell face.
 
No rounding of the electrodes. A hint of tan on the side of the porcelain facing the intake valve. Good luck on that one. Fractured porcelain and so on. 
 
From 9,000 on up, a good CD or CD with multi spark is a must, both power wise and misfire wise.
 
So, a dark plug that has idled for just a second or so will look bad because the nose temp has dropped out of the operating temp range and collects phosphors from car gas or lead compounds fro avgas. it just looks bad. It will clean up when used hard again.
 
Lynn E. Hanover
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